It is twenty years since the events in The Song of Mavin Manyshaped, twenty years since Mavin made her promise to Himaggery, that they would meet in Pfarb Durim. Now it is time to meet again.
Mavin goes to the hotel where they saw each other last and waits, but Himaggery does not come. When she checks for messages, there is one from the Seer Windlow, their old friend, telling her that there will be a messenger waiting at the monuments outside of the city.
When the messenger arrives, it is a famous Shifter, Throsset of Dowes, one who escaped Danderbat keep when Mavin was very young. She bears a letter, written by Himaggery eight years ago, which tells that he is going on a quest, and that if she receives the letter, he is probably dead. Throsset says that he is not, that they have had signs from Seers and Necormancers that Himaggery lives, and Mavin must find him.
She travels north to see the wizard Chamferton, where Himaggery apparently went. On the way, she comes to a strange lake, where there are many poles with faces pinned to them. A pair of Harpies are by the lake, talking. One is Pantiquod, mother of Huld the Demon, the other is her daughter Foulitter. Pantiquod asks for the use of a wand, and they use it to question some of the faces around the lake, which answer them. Mavin sees that one of them is Himaggery's.
When Pantiquod leaves, Mavin rises up and attacks Foulitter, taking the wand and questioning Himaggery, but she learns only that he is beneath Bartelmy's Ban, which she does not understand. She continues on to Chamferton's Fortress, taking the wounded Harpy with her, and finds him to be sly and secretive.
He tells her that Himaggery went further north to find a road, upon which groups of blindfolded people run. She searched for it, and finds the runners, but still has no luck with finding Himaggery until she meets with a Dervish named Bartelmy. Following the Dervish she sees a magical creature, a unicorn, and remembers a time years earlier. She had found that unicorn before, and run with him for a time. Now she changes her shape to match his and runs with him again.
One day she hears a voice calling her up from that shape, and Bartelmy speaks to her. Mavin learns that the unicorn is Himaggery, that he is not really a unicorn, that he only believes he is, and so does everything else. This is to hide him from danger. There is a tower nearby, surrounded by shadow. The shadow moves and drifts, and anything that blunders into it immediately destroys itself. Himaggery tried to enter the tower, but the shadow stopped him, and now if he comes back to his true shape, it will kill him.
Mavin must take Himaggery, and another in the shape of a Pombi, far away and bring them back to themselves. She discovers as she travels that the shadow will not lie on the road, and so they travel upon it. She risks bringing the man shaped as a pombi back to himself and finds that the man is not troubled by the shadow. He is the Wizard Chamferton, and his borther is the one pretending to be him that Mavin met.
The Lake of Faces is dangerous, every time the face is questioned, the person who owns the face loses a year of their life. They must go and destroy the faces, and Chamferton must defeat his brother. Mavin shifts herself longer legs so that she can run ahead and Himaggery and Chamferton will follow. On the way to the Lake, Mavin meets again with the Shadow People, who celebrate because she is pregnant. She had no idea before, and now has a proble, because women should not shifts while pregnant, lest they harm the child.
Mavin is worried that the Harpies will try to avenge themselves on her, and she cannot defend herself if she cannot shift. The make it to the Lake of Faces and the Shadow People help her pull down the faces of herself and Himaggery. When Chamferton arrives, they devise a plan to take back the wand which will allow him to defeat his brother. In doing so, they kill Foulitter, but Pantiquod is still out there, and Mavin must avoid both her and the Shadow on her journey.
While she travels, she watches the Shadow at the side of the road. She see that it does not attack directly, but lays waiting for something to walk into it. She also sees that there is always a way through, if you're careful. While walking down the centre of the road, she hears the cry of a Harpie, and sees that Pantiquod has brought all her relatives to the attack.
Mavin steps off the road and works her way through the Shadow to free area in the middle of a thick patch, and waits with a large branch. When the Harpies descend, some land in the Shadow and others she knocks into it, where they destroy themselves. To her surprise, the Shadow soon lifts off and returns to the north, leaving her alone. It sought a target, and fed near that target, now it is sated.
She waits until they have reached the safety of Windlow's school before restoring Himaggery to his own shape. In the coming days, Throsset and Windlow both realise that she is pregnant, but Hinaggery doesn't seem to. She comes to realise that he likes the idea of her better than the reality, and that he sees her only through his romantic ideas. He wants her to come and be his wife, settling comfortably. She wants to continue her adventures.
In the end, she rides away, leaving him without telling him that she is pregnant.